granicus.if.org Git - postgresql/blob - src/include/port/atomics/generic-acc.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * generic-acc.h
   4  *        Atomic operations support when using HPs acc on HPUX
   5  *
   6  * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  * NOTES:
  10  *
  11  * Documentation:
  12  * * inline assembly for Itanium-based HP-UX:
  13  *   http://h21007.www2.hp.com/portal/download/files/unprot/Itanium/inline_assem_ERS.pdf
  14  * * Implementing Spinlocks on the Intel (R) Itanium (R) Architecture and PA-RISC
  15  *   http://h21007.www2.hp.com/portal/download/files/unprot/itanium/spinlocks.pdf
  16  *
  17  * Itanium only supports a small set of numbers (6, -8, -4, -1, 1, 4, 8, 16)
  18  * for atomic add/sub, so we just implement everything but compare_exchange
  19  * via the compare_exchange fallbacks in atomics/generic.h.
  20  *
  21  * src/include/port/atomics/generic-acc.h
  22  *
  23  * -------------------------------------------------------------------------
  24  */
  25
  26 #include <machine/sys/inline.h>
  27
  28 #define pg_compiler_barrier_impl()      _Asm_sched_fence()
  29
  30 #if defined(HAVE_ATOMICS)
  31
  32 /* IA64 always has 32/64 bit atomics */
  33
  34 #define PG_HAVE_ATOMIC_U32_SUPPORT
  35 typedef struct pg_atomic_uint32
  36 {
  37         volatile uint32 value;
  38 } pg_atomic_uint32;
  39
  40 #define PG_HAVE_ATOMIC_U64_SUPPORT
  41 typedef struct pg_atomic_uint64
  42 {
  43         /*
  44          * Alignment is guaranteed to be 64bit. Search for "Well-behaved
  45          * application restrictions" => "Data alignment and data sharing" on HP's
  46          * website. Unfortunately the URL doesn't seem to stable enough to
  47          * include.
  48          */
  49         volatile uint64 value;
  50 } pg_atomic_uint64;
  51
  52
  53 #define MINOR_FENCE (_Asm_fence) (_UP_CALL_FENCE | _UP_SYS_FENCE | \
  54                                                                  _DOWN_CALL_FENCE | _DOWN_SYS_FENCE )
  55
  56 #define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U32
  57 static inline bool
  58 pg_atomic_compare_exchange_u32_impl(volatile pg_atomic_uint32 *ptr,
  59                                                                         uint32 *expected, uint32 newval)
  60 {
  61         bool    ret;
  62         uint32  current;
  63
  64         _Asm_mov_to_ar(_AREG_CCV, *expected, MINOR_FENCE);
  65         /*
  66          * We want a barrier, not just release/acquire semantics.
  67          */
  68         _Asm_mf();
  69         /*
  70          * Notes:
  71          * DOWN_MEM_FENCE | _UP_MEM_FENCE prevents reordering by the compiler
  72          */
  73         current =  _Asm_cmpxchg(_SZ_W, /* word */
  74                                                         _SEM_REL,
  75                                                         &ptr->value,
  76                                                         newval, _LDHINT_NONE,
  77                                                         _DOWN_MEM_FENCE | _UP_MEM_FENCE);
  78         ret = current == *expected;
  79         *expected = current;
  80         return ret;
  81 }
  82
  83
  84 #define PG_HAVE_ATOMIC_COMPARE_EXCHANGE_U64
  85 static inline bool
  86 pg_atomic_compare_exchange_u64_impl(volatile pg_atomic_uint64 *ptr,
  87                                                                         uint64 *expected, uint64 newval)
  88 {
  89         bool    ret;
  90         uint64  current;
  91
  92         _Asm_mov_to_ar(_AREG_CCV, *expected, MINOR_FENCE);
  93         _Asm_mf();
  94         current =  _Asm_cmpxchg(_SZ_D, /* doubleword */
  95                                                         _SEM_REL,
  96                                                         &ptr->value,
  97                                                         newval, _LDHINT_NONE,
  98                                                         _DOWN_MEM_FENCE | _UP_MEM_FENCE);
  99         ret = current == *expected;
 100         *expected = current;
 101         return ret;
 102 }
 103
 104 #undef MINOR_FENCE
 105
 106 #endif /* defined(HAVE_ATOMICS) */